Hammer for hammermill



H. C. POLLlTZ HAMMER FOR HAMMERMILL Filed Dec.

July 26, 1966 .6 l W F m F 9 O O 0 INVENTOR HAROLD C. POLLITZ ATTORNEYUnited States Patent 3,262,646 HAMMER FOR HAMMERMILL Harold C. Pollitz,Cedar Rapids, Iowa, assignor to Iowa Manufacturing Company of CedarRapids, Iowa, Cedar Rapids, Iowa, a corporation of Iowa Filed Dec. 26,1962, Ser. No. 247,232 9 Claims. (Cl. 241197) a typical hammermill it iscustomary to construct each hammer itself in two parts, a permanenthammer arm and a replaceable tip therefor. Many ways have been devisedto attach the tip to the arm so that former may be removed as easily aspossible and in the least possible time. Whatever the way employed, themost important thing is to avoid having first to remove the entirehammer itself from the mill before the tip may be detached therefrom.For this purpose the prior art illustrates a wide variety of detachablejoints between the arms and tips, but these usually additionally requirevarious looking means, such as bolts, keys, cotter pins, retainingplates and the like. But such all add to the complexity and cost of thehammer assembly itself and also increase the time and labor necessary tochange tips. Furthermore, especially when an interlocking joint is usedbetween the hammer arms and tips, fine dust finds its way into the jointduring crushing and causes liming of the tip to the arm, greatlyincreasing the difficulty of removing the former.

In order to cut tip removal time and effort to a minimum and to reducethe cost and complexity of the hammer assembly itself, the presentinvention provides a simple interlocking joint between the hammer armand tip so that the latter is attached or removed, as the case may be,simply by sliding it transversely of the hammer arm. Additionally, thejoint, which may be of the T- shaped variety, is formed so that when thearm and tip are assembled, an integral wall on the arm at one transverseend of the joint overlaps the latter so that both transverse ends of thejoint are closed to access by fine dust in order largely to prevent anyliming between the arm and tip during crushing. Furthermore, the outerfaces of the arm and tip end walls are located so that when, as iscustomary, a row of several hammers are swingably mounted side by sideon a common axis, the outer surfaces of the end walls of adjacenthammers oppose and are closely spaced from each other. Accordingly,since centrifugal force arising from rotation of the hammermill spinnerto which the hammers are attached maintains the row of hammerssubstantially side by side during operation, the aforesaid opposed,closely spaced end walls preyent accidental detachment of any of thetips from the hammer arms. This is accomplished no matter how the innerhammers of the row may be mounted on their axis; however, the two outerhammers at each end of the row must be mounted with their arm end wallsfacing the respective adjacent end walls of the hammermill itself inorder to prevent any transverse movement of the tips sufiicient tostrike the end walls of the mill. When the mill is stopped, the hammersmay be rotated on their axis with respect to each other and the tipssimply and quickly knocked off for replacement, thus greatly reducinglabor and shut-down time. Finally, the construction of the presentinvention also provides several collateral advantages, namely, the armand tip end walls add to the strength of each and particularly to thatof the joint therebetween, maximum weight is carried in the hammer tipitself, and loss of metal on the latter does not weaken the joint.

3,262,645 Patented July 26, 1966 Accordingly, the primary object of thepresent invention is to provide a transverse joint between the arm andremovable tip of a hammer for a hammermill which both increases thestrength of the arm, tip and joint and the weight of the tip and whichincorporates means at each end of the joint and integral with the armand tip both to close the ends of the joint and to maintain the tip onthe hammer during operation of the mill when several hammers are mountedside by side on a common axis.

A further object of the present invention is the provision of a hammerarm and removable tip for a hammermill having an inter-locking jointtherebetween, the tip being slideably disengageable by movement theeroftransversely of the direction of the operative movement of the hammer inthe mill, the arm being provided with a wall at one transverse end ofthe joint closing that end and the tip being provided with acomplementary wall at the other transverse end of the joint closing thatend in order to reduce access to the joint by dust during operation ofthe mill and to provide means to retain the tip on the arm when severalhammers are operatively assembled side by side on a common axis in themill.

Other and further objects, features and advantages of the presentinvention will become apparent from the preferred =form thereofhereafter described read in conjunc tion with the following drawings, inwhich:

FIGURE 1 is an end elevational view of a typical hammermill with one endwall removed;

FIGURE 2 is an exploded, perspective view of a hammer arm and removabletip employing the features of the present invention; and

FIGURE 3 is a side elevational view of a portion of the hammermill ofFIGURE 1 illustrating several of the hammers shown in FIGURE 2 mountedaccording to the present invention.

Inasmuch as hammermills generally, as Well as their operation, are wellknown (see, e.-g., US. Patent No.

2,563,958 to Pollitz), only a relatively brief discussion thereof isneeded here as a-setting for a more detailed description of the presentinvention. illustrated specifically in FIGURE 1 is of a well-known,conventional type employing an upright, generally rectangular housing 10having side walls 11 and 12, end walls 13 and 14, top frame 15 and anopen bottom. A spinner assembly 16, axially mounted onaheavy, horizontalshaft 17 journaled at each end in end walls 13 and 14 and driven bysuitable means (not shown) in the Spinner assembly 16 comprises a row ofdisc-like members 18 extending radially of shaft 17 and spaced axiallytherealong. Several sets of holes 19 through discs 18 are spaced aboutand from shaft 17, each set being axially aligned to receive ahorizontal hammer mounting pin 19' therethrough, suitably securedagainst axial movement, upon which a row of hammers 20 are joumaled attheir inner radial ends, each hammer 20 of each row being straddled by apair of adjacent discs 18, the spacing between the latter being somewhatgreater than the overall transverse dimension of each hammer 20. Astationary breaker and feed assembly, in the form of a generallycylindrical cage-like structure, is disposed in housing 10 substantiallyabout and spacedly from the entire peripheral path of the outer ends ofhammers 20 during rotation of spinner assembly 16. The breaker assemblyextends rectilinearly between end walls 13 and 14 parallel to Thehammermill in their travel. The inclination of breaker plate 21 is madeadjustable for well-known reasons by suitable means 22. To the portionof top frame immediately above the space between breaker plate 21 andhammers attheir aforesaid point is attached a feed chute 23 and theremainder of the space between feed chute 23 and side wall 12 is closedby an outwardly convex cover 24, horizontally hinged at adjacent the topedge of side wall 12 for access to the interior of housing 10. The innersurface of cover 24 carries a typical assembly of liner plates 25extending transversely between end walls 13 and 14. Breaker plate 21,feed chute 23 and liner plates 25 thus surround the upper half ofspinner assembly 16. The lower half therebelow employs a series of gratebars 26 extending transversely between end walls 13 and 14 and spacedlypositioned side by side to form an upwardly opening concave gratesurface from the lower end of breaker plate 21 to the lower end of linerplates 25, but spaced much more closely to the path of travel of theouter ends of hammers 20 than the upper half in order to permit thehammer ends to mill or grind aggregate against grates 26, as describedin the aforesaid patent to Pollitz. Grate bars 26 thus providecommunication with the open bottom of housing 10, and if desired, forWellknown purposes, the spacing of the individual bars 26 may beprogressively increased and changed to meet the gradation requirement ofthe a'ggregrate produced.

Turning next to the individual hammers 20 themselves and with referenceto the position thereof illustrated in FIGURES 2 and 3. each hammercomprises a hammer arm 30, generally rectangular in cross section, and aremovable hammer tip 31 of generally cubical shape. Arm is formed with apair of opposite, parallel side Walls 32 and 33, spaced apart somewhatless than the spacing between adjacent discs 18, and perpendicularlybored at 34 adjacent the inner radial end of arm 30 to receive one ofhammer pins 19 therethrough so that hammer 20 may be swingably mountedthereon. The remaining side walls 35 and 36 of arm 30 are also paralleland curvingly converge to round off the inner end of arm 30. The outerradial end of arm 30 is provided with a suitable, symmetrically shapedupright slot 37, generally of a T shape, having its cross barhorizontally and centrally disposed between side walls 35 and 36. T-slot37 extends uniformly across arm 30 from side wall 32 parallel to sidewalls 35 and 36 to the plane of side wall 33, the upper corners of itscross bar being rounded. The end of T-slot 37 in the plane of side wall33 is closed by an end wall 38 formed integrally with arm '30 and T-slot37 and provided with an outer end face 39 spaced i outwardly from andparallel to side wall 33 and an inner end face 40 in the plane of sidewall 33 and forming the .closed end of T-slot 37. The bifurcated end ofarm 30 formed by T-slot 37 has the outer radial end of each half thereofforming its stroke portion also rounded .to form a pair of laterallyspaced retaining lips 41, extending from side wall 32 parallel to T-slot37 to end face 40, in the form of depending half round sections havingtheir inner lateral edges forming the juncture between the cross bar andstroke of T-slot 37 and their outer lateral edges lying in the planes oftheir respective adjacent side walls 35 and 36. The top of end wall 38is radiused into side wall 33 and its bottom is horizontally faced at 42flush with the lowermost points of retaining lips 41. The lateral faces43 and 44 of end wall 38 are also preferably spaced outward from andparallel to side walls 35, 36, the portions thereof above retaining lips41 being carried across side walls 35, 36 to side wall 32 to form withthe outer lateral edges of retaining lips 41 a pair of downwardly facingshoulders 45, 46 extending in the same plane as the lower face of thecross bar of T-slot 37 from end face 49 to side wall 32.

Hammer tip 31 is formed with a pair of opposite, parallel side walls 51,52 flush with lateral faces 43 and 44 of arm end wall 38, and a pair ofopposite end walls facing seat 55 and a flat vertical end face 56parallel to tip end wall 53. The remaining portion of the inner radialend of tip 31 is formed with a symmetrically shaped, integral T-rib 57,complementary to T-slot 37, having its cross bar and rib horizontallyand centrally disposed between tip side walls 51, 52. T-rib 57 extendsuniformly across tip 31 from end face 56 parallel to side walls 51, 52 adistance equal to the length of T-slot 37, terminating so as to providea vertical inner end face 58 parallel to end wall 54. Accordingly, theupper portion of end wall 54 and end face 58 together provide an endwall 59, equal in thickness to arm end wall 38 and closing the adjacentend of T-rib 57. The upper portions of tip side walls 51 and 52 are alsoinwardly relieved to provide a pair of horizontal, upwardly turned seats60, 61, spaced above seat 55 a distance equal to the height of shoulders45, 46 above lower face 42 of arm end Wall 38, the top of end wall 59being beveled at each corner thereof downwardly to seats 60, 61. Thuswhen T-rib 57 is slideably fully engaged with T-slot 37, arm shoulders45, 46 will register with and fully receive tip seats 60, 61, and lowerface 42 of arm end wall 38 will register with and fully receive tip seat55; end face 32 of T-slot 37 will abut or at least oppose inner end face58 of end wall 59 and end face 56 of T- rib 57 will abut or at leastoppose inner end face 40 of arm end wall 38; lateral faces 43, 44 of thelatter will be flush with tip side walls 51, 52, respectively, and outerend face 39 of arm wall 38 will be flush with tip end wall 53, thusentirely closing the joint between arm 30 and tip 31. At the same timethe outer face 54 of end wall 59 will be spaced outwardly of andparallel to arm side wall 32 the same distance outer end face 39 of armend Wall 38 is from arm side wall 33. Arm end Wall face 39 and tip endwall 53, on the one hand, and tip end Wall 54 on the other, thus formthe maximum transverse dimension of each hammer 20, which dimension isapproximately equal to the space between adjacent discs 18. Finally, theouter radial end or face of tip 31 is curved between side wall 51 and 52on a radius swung from the axis of bore 34 in order to provide a millingor grinding surface 70 thereon. The latter in turn may be provided ifdesired, with a relatively shallow, concave groove 71 therein of halfround section extending thereacross between end walls 53 and 54 midwaybetween side walls 51 and 52 in order to aid the grinding action ofhammers 28 against grate bars 26.

Mounting of hammers 25 on hammer pins 19' between adjacent discs 18 isaccomplished in the usual manner. However, referring to FIGURE 3, it isnecessary that the hammer at each end of each row of hammers on spinnerassembly 16 be positioned with its outer end face 39 of arm end Wall 38facing the adjacent inner face of end wall 13 or 14, as the case may be,of housing 10. In this manner no transverse movement of tips 31 relativeto arms 30 can cause interference of the former with end walls 13 or 14.The inner hammers of each row, on the other hand, may be positionedeither way on their hammer pins 19, inasmuch as since during operationof the mill centrifugal force maintains the hammers of each rowsubstantially side by side radially outwards of shaft 17, any transversemovement of tips 31, even enough for two adjacent tips to touch, willnot impair the operation of the hammers themselves. Such transversemovement as may occur will be very little, owing to the close spacing ofthe adjacent end faces of the tips of adjacent hammers, thus insuringthat each tip remains attached to its hammer arm even though no othersecuring device is used. Passage of the grinding ends 70 over grate bars26 provides a progressive reduction in size of the aggregate initiallyshattered by hammers 20 or against breaker plate 21.

When the tips must be replaced, stopping the mill permits the individualhammers of each row to be rotated on their pins 19' relative to eachother in order to expose end walls 53 of the tips. A blow on the latterwill quickly detach the tip from the arm with little difficulty arisingfrom liming of T-rib 57 in T-slot 37, owing to the closure of thetransverse end of the T-joint by end walls 38 and 59 of arms 30 and tips31, respectively. It will, of 'course, be understood that other suitablejoints could be employed between arms 30 and tips 31 solong as theypermit the closure of each transverse end thereof in the manner of thepresent invention. Thus, both from the standpoint of initialinstallation as well as from the standpoint of replacement, it will beapparent that the present invention provides a hammer arm and tipcombination providing maximum ease of tip replacement and requiring aminimum of mill shutdown time and labor.

While the present invention has been described with reference to aparticular embodiment and detailed descriptive language has been used,it is not so limited. Instead, the following claims are to be read asencompassing such modifications and adaptations of the invention aswould ordinarily occur to one in the art.

I claim:

1. A hammer for use in a hammer mill comprising a hammer arm mountableadjacent one end for swinging movement in a first plane and areplaceable hammer tip removably secured radially outwards from theother end of said arm by means preventing detachment of said tip fromsaid arm in a direction radially of the latter, said means including aslideably interlocking joint between the respective adjacent radiallydisposed ends of said arm and tip, said joint being formed by acontoured arm portion and a complementarily contoured tip portion, eachof said portions being formed integrally with respectively said arm andtip so that said joint extends substantially across said arm and tip ina direction transversely of said first plane and being slideable withrespect to each other in said last named direction in order to detachsaid tip from said arm, one pair of the respective opposite transverseends of said portions being open to permit slideable disengagement ofsaid portions and each of the other pair of the respective oppositetransverse ends of said portions being closed by an end wall formedintegrally therewith, said end walls forming the maximum transversedimensions of said hammer relative to said first plane.

2. The device of claim 1 wherein each of said contoured portions extendsacross said arm and tip respectively in a direction substantially normalto the radial axis of said arm and wherein said joint provides the solemeans to retain said arm and tip in interlocking assembled relationship.

3. The device of claim 2 wherein said tip end wall forms the whole ofone of the transverse ends of said tip and lies in a second planeparallel to said first plane and said arm end wall and the face of theother transverse end of said tip each lie in a third plane parallel tosaid first plane with their respective adjacent edges both adjoining andflush with each other, and wherein the leading and trailing walls ofsaid tip relative to swinging movement of said hammer each lie in aplane transversely of said first plane and both adjoin and are flushwith the respective immediately adjacent portions of the leading andtrailing walls of said arm.

4. The device of claim 3 wherein the contour of one of said portions isgenerally in the form of a T-shaped slot extending transversely withrespect to said first plane of said adjacent end of said one portion,and wherein the contour of the other of said portions is generally inthe form of a complementary T-shaped rib extending transversely withrespect to said first plane of said adjacent end of said other portionand slidably engageable with said slot.

5. The device of claim 4 wherein the outer radially disposed end of saidtip is provided with an arcuate grinding surface lying substantially inthe path traversed by said tip end during swinging movement of saidhammer and extending rectilinearly transversely of said first plane,said surface having a transversely extending groove therein facingradially outward from said surface and disposed substantially midwaybetween the leading and trailing edges of said surface relative toswinging movement of said hammer. I

6. In a hammer mill comprising an assembly having a spinner rotatableabout a horizontal axis, at least one horizontal hammer axis on saidspinner radially spaced from said spinner axis, and a plurality ofhammers side by side on said hammer axis, each of said hammerscomprising a hammer arm mounted at its inner radial end for swingingmovement about said hammer axis in a vertical first plane relative toeach other and to said spinner axis and a replaceable hammer tip securedto the outer radial end of said arm, said mill including a pair ofstationary end walls having opposed inner faces, each face being'adjacent said tip of the hammer at one transverse end of said hammeraxis and parallel to said first plane; the combination therewith ofmeans removably attaching each of said hammer tips to its respectivehammer arm and preventing detachment of said tip from said arm in adirection radially of the latter, said means including a slideablyinterlocking joint between the adjacent radially disposed ends of saidarm and tip, said joint being formed by a contoured arm portion and acomplementarily contoured tip portion, each of said portions beingformed integrally with respectively said arm and tip so that said jointextends substantially across said arm and tip in a directiontransversely of said first plane and being slideable with respect toeach other in said direction to detach said tip from said arm, one pairof the respective opposite transverse ends of said portions being opento permit slidable disengagement of said portions and each of the,

other pair of the respective opposite transverse ends of said portionsbeing closed by an end wall formed integrally therewith, said end wallsforming the maximum transverse dimensions of said hammer relative tosaid first plane, each pair of adjacent hammers on said hammer axishaving their adjacent end walls opposing and closely spaced from eachother efiective to prevent slideable disengagement of said arms and tipsduring operative rotation of said spinner without need to employadditional means to prevent said disengagement, the hammer at eachtransverse end of said hammer axis having its arm end wall opposing andclosely spaced from the hammermill end wall adjacent thereto.

7. The device of claim 6 wherein said tip end wall forms the whole ofone of the transverse ends of said tip and lies in a second planeparallel to said first plane and said arm end wall and the wall of theother transverse end of said tip each lie in a third plane parallel tosaid first plane with their respective adjacent edges both adjoining andflush with each other, and wherein the leading and trailing walls ofsaid tip relative to swinging movement of said hammer each lie in aplane transversely of first said plane and both adjoin and are flushwith the respective immediately adjacent portions of the leading andtrailing walls of said arm.

8. The device of claim 7 wherein the con-tour of one of said portions isgenerally in-the form of a T-shaped slot extending transversely withrespect to said first plane of said adjacent end of said one portion,and wherein the contour of the other of said portions is generally inthe form of a complementary T-shaped rib extending transversely withrespect to said first plane of said adforming an upwardly openingconcave grate surface disposed beneath said rotary assembly and closelyspaced from the path of said hammers during operative rotation of saidrotary assembly and wherein the outer radially disposed end of said tipis provided with an arcuate grinding surface lying substantially in thepath traversed by said tip end during swinging movement of said hammerrelative to its hammer axis and extending rectilinearly transversely ofsaid first plane, said surface having a transversely extending groovetherein facing radially outward from said surface and disposedsubstantially midway between the leading and trailing edges of saidsurface relative to rotation of said rotary assembly.

References Cited by the Examiner UNITED STATES PATENTS 1,456,987 5/ 1923Lucas 241-197 2,318,219 5/1943 Harris 241197 2,514,111 2/ 1948 Wilson241194 X 2,568,077 9/1951 Loufek 241197 10 3,179,344 4/1965 Morel 241197FOREIGN PATENTS 658,810 4/1938 Germany.

15 ROBERT C. RIORDON, Primary Examiner.

J. SPENCER OVERHOLSER, Examiner.

D. C. CHAMPION, H. F. PEPPER, 112., Assistant Examiners.

1. A HAMMER FOR USE IN A HAMMER MILL COMPRISING A HAMMER ARM MOUNTABLEADJACENT ONE END FOR SWINGING MOVEMENT IN A FIRST PLANE AND AREPLACEABLE HAMMER TIP REMOVABLY SECURED RADIALLY OUTWARDS FROM THEOTHER END OF SAID ARM BY MEANS PREVENTING DETACHMENT OF SAID TIP FORMSAID ARM IN A DIRECTION RADIALLY OF THE LATTER, SAID MEANS INCLUDING ASLIDEABLY INTERLOCKING JOINT BETWEEN THE RESPECTIVE ADJACENT RADIALLYDISPOSED ENDS OF SAID ARM AND TIP, SAID JOINT BEING FORMED BY ACONTOURED ARM PORTION AND A COMPLEMENTARILY CONTOURED TIP PORTION, EACHOF SAID PORTIONS BEING FORMED INTEGRALLY WITH RESPECTIVELY SAID ARM ANDTIP SO THAT SAID JOINT EXTENDS SUBSTANTIALLY ACROSS SAID ARM AND TIP INA DIRECTION TRANSVERSELY OF SAID FIRST PLANE AND BEING SLIDEABLE WITHRESPECT TO EACH OTHER IN SAID LAST NAMED DIRECTION IN ORDER TO DETACHSAID TIP FROM SAID ARM, ONE PAIR OF THE RESPECTIVE OPPOSITE TRANSVERSEENDS OF SAID PORTIONS BEING OPEN TO PERMIT SLIDEABLE DISENGAGEMENT OFSAID PORTIONS AND EACH OF THE OTHER PAIR OF THE RESPECTIVE OPPOSITETRANSVERSE ENDS OF SAID PORTIONS BEING CLOSED BY AN END WALL FORMEDINTEGRALLY THEREWITH, SAID END WALLS FORMING THE MAXIMUM TRANSVERSEDIMENSIONS OF SAID HAMMER RELATIVE TO SAID FIRST PLANE.